Effect of Preparation Technique on the Performance of Ni and Ce Incorporated Modified Alumina Catalysts in CO2 Reforming of Methane

摘要

Performances of modified sol-gel alumina (MSGA) based catalysts, synthesized in an inert atmosphere and activated by Ni and Ce were investigated in CO2 reforming of methane. Two different incorporation methods were used to dope Ce into the structure of the catalysts: (i) simultaneous impregnation of Ce together with Ni (Ni-Ce@MSGA), (ii) one-pot synthesis of Ce incorporated alumina support material (Ni@Ce-MSGA). In the second case Ni was impregnated on the Ce-MSGA support. Synthesized catalysts were characterized using TPR, XRD, N-2 adsorption/desorption, pyridine adsorbed DRIFT, CO2-TPD techniques. These analyses showed that the synthesized catalysts possessed reduced Ni particles, as well as mesoporous structure, Lewis acid sites and moderate basicity. The modified sol-gel alumina and modified sol-gel Ce-MSGA supported catalysts showed stable activity in CO2 reforming of methane. Ce incorporation improved catalytic activity of the synthesized catalysts and reduced the occurrence of reverse water gas shift reaction. Ni-Ce@MSGA catalyst decreased the CO2/CH4 conversion ratio much higher than Ni@Ce-MSGA catalyst. Coke analysis were determined using TGA/DTA, XRD, and SEM analysis. Especially, simultaneous impregnation of Ce and Ni catalyst inhibited coke deposition significantly due to lattice oxygen of ceria. However, coke deposition over Ni@Ce-MSGA catalyst was higher than Ni@MSGA catalyst since Ni@Ce-MSGA catalyst has higher nickel crystal size than that of Ni@MSGA catalyst.